As someone whose spouse's usual attire is t-shirts, slacks, and birkenstocks without socks, the idea that you can make judgements about someone based on their clothing raises my hackles. Clothing does not designate "riff raff" behavior does.
I do admit that my husband dresses up to travel (not a suit and tie, but a nice button down, or polo shirt). My children also dress "appropriately" for travel. We've run into parishoners in airports and their first comment is "Deacon Dan's wearing socks." It's not always easy to have a t-shirt spirituality